Optical Coherence Tomography (OCT) is an optical imaging technique frequently used to image biological tissue and is capable of acquiring high-resolution images. Usually broadband light having a coherence length of 1-10 μm is scanned across an area of interest, typically up to 10 mm×10 mm, to generate an OCT image to depths of 1-3 mm. The light penetrates into material at an area of interest where, dependent on local material properties, a portion of the light is reflected or backscattered. The OCT system combines the reflected or backscattered light with reference light in an interferometer setup, which results in interference between light reflected from the reference and the material if the path length differences are less than the coherence length of the light. By detecting the light backscattered from the sample at a number of different path lengths, a depth resolved image with an imaging depth of 1-3 mm can be obtained.
OCT can be used to identify diseased tissue and may be used to identify, for example, tumours during surgery. However, the available time during surgery is very limited and, using known OCT technology, in many cases, it is not practical to scan multiple areas simultaneously. The characterisation of multiple areas of a material simultaneously using known OCT technologies requires a complex optical design, which is unsuitable for portable implementation.